addressing issue 4355 (#4414)
addressing issue 4355 (#4414)

Addressing changes needed to fix [issue 4355: problem enabling zoom on Image_url object](https://github.com/bokeh/bokeh/issues/4355#)
rs2/bokeh,phobson/bokeh,DuCorey/bokeh,ericmjl/bokeh,ericmjl/bokeh,Karel-van-de-Plassche/bokeh,schoolie/bokeh,clairetang6/bokeh,percyfal/bokeh,Karel-van-de-Plassche/bokeh,philippjfr/bokeh,dennisobrien/bokeh,jakirkham/bokeh,bokeh/bokeh,clairetang6/bokeh,dennisobrien/bokeh,jakirkham/bokeh,rs2/bokeh,Karel-van-de-Plassche/bokeh,schoolie/bokeh,philippjfr/bokeh,azjps/bokeh,aavanian/bokeh,DuCorey/bokeh,justacec/bokeh,bokeh/bokeh,DuCorey/bokeh,philippjfr/bokeh,aiguofer/bokeh,ptitjano/bokeh,ptitjano/bokeh,justacec/bokeh,timsnyder/bokeh,draperjames/bokeh,bokeh/bokeh,phobson/bokeh,percyfal/bokeh,aiguofer/bokeh,bokeh/bokeh,dennisobrien/bokeh,aiguofer/bokeh,Karel-van-de-Plassche/bokeh,percyfal/bokeh,azjps/bokeh,jakirkham/bokeh,aavanian/bokeh,rs2/bokeh,Karel-van-de-Plassche/bokeh,aiguofer/bokeh,ptitjano/bokeh,stonebig/bokeh,stonebig/bokeh,rs2/bokeh,aiguofer/bokeh,phobson/bokeh,bokeh/bokeh,phobson/bokeh,azjps/bokeh,mindriot101/bokeh,timsnyder/bokeh,ericmjl/bokeh,timsnyder/bokeh,ericmjl/bokeh,clairetang6/bokeh,jakirkham/bokeh,ptitjano/bokeh,azjps/bokeh,draperjames/bokeh,justacec/bokeh,percyfal/bokeh,schoolie/bokeh,aavanian/bokeh,stonebig/bokeh,philippjfr/bokeh,schoolie/bokeh,justacec/bokeh,dennisobrien/bokeh,aavanian/bokeh,phobson/bokeh,mindriot101/bokeh,DuCorey/bokeh,azjps/bokeh,stonebig/bokeh,philippjfr/bokeh,schoolie/bokeh,mindriot101/bokeh,jakirkham/bokeh,DuCorey/bokeh,draperjames/bokeh,rs2/bokeh,aavanian/bokeh,ptitjano/bokeh,mindriot101/bokeh,dennisobrien/bokeh,clairetang6/bokeh,timsnyder/bokeh,ericmjl/bokeh,percyfal/bokeh,timsnyder/bokeh,draperjames/bokeh,draperjames/bokeh